Fahrenheit to Celsius Converter

How to convert degrees Fahrenheit to degrees Celsius

The degrees Fahrenheit and degrees Celsius scales do not share a zero point, so converting between them takes two steps rather than a single multiplication. The formula is (°F − 32) × 5/9 = °C. Because the two scales also use different degree sizes, no single ratio can describe the relationship, which is why a degree Fahrenheit value cannot simply be scaled up or down.

The calculator above applies this automatically as you type, but it is worth knowing the arithmetic if you need to sanity-check a figure or work one out without a device to hand.

Worked examples

68 °F to °C: apply (°F − 32) × 5/9 = °C to 68, which gives 20 °C.

98.6 °F to °C: apply (°F − 32) × 5/9 = °C to 98.6, which gives 37 °C.

350 °F to °C: apply (°F − 32) × 5/9 = °C to 350, which gives 176.66667 °C.

Fahrenheit to Celsius conversion table

The values below are calculated with the same function as the converter above, so they agree to the digit. The range covers everyday weather and cooking temperatures as well as the fixed points of both scales.

What is a degree Fahrenheit?

The Fahrenheit scale puts water's freezing point at 32 and its boiling point at 212, giving 180 degrees between them. A Fahrenheit degree is therefore five ninths the size of a Celsius degree, which is why conversion needs both a multiplication and an offset.

Where the degree Fahrenheit came from

Daniel Gabriel Fahrenheit devised the scale around 1724, anchoring 0 to the temperature of a brine mixture (the coldest he could reliably reproduce) and setting roughly 96 for human body temperature. Later refinement moved body temperature to 98.6 and fixed the scale on water's freezing and boiling points instead.

Where degrees Fahrenheit are used today

Fahrenheit is the everyday scale in the United States and a few territories. American weather reports, oven dials, and thermostats all use it, which makes Fahrenheit-to-Celsius one of the most searched conversions on the internet.

• Water freezes at 32 °F and boils at 212 °F
• Normal body temperature is 98.6 °F
• A warm summer day is around 77 °F

What is a degree Celsius?

The Celsius scale places 0 at the freezing point of water and 100 at its boiling point at standard atmospheric pressure. A Celsius degree is the same size as a kelvin, so the two scales differ only by an offset of 273.15.

Where the degree Celsius came from

Anders Celsius proposed the scale in 1742, but with the numbers reversed: 0 was boiling and 100 was freezing. It was inverted shortly after his death, and the scale was called centigrade until 1948, when it was renamed in his honour to avoid confusion with an angular unit of the same name.

Where degrees Celsius are used today

Celsius is the everyday temperature scale nearly everywhere in the world, and the scientific standard alongside kelvin. Weather forecasts, oven settings, and body temperature outside the US are all in Celsius.

• Water freezes at 0 °C and boils at 100 °C
• Normal body temperature is about 37 °C
• A warm summer day is around 25 °C

When you actually need this conversion

degrees Fahrenheit belong to the imperial / us customary system and degrees Celsius to the metric (si) system, so this conversion turns up whenever information crosses between countries that measure differently.

Accuracy, precision, and rounding

The Celsius and Fahrenheit relationship is exact, so conversion introduces no error of its own. What it does introduce is spurious precision: converting a weather figure rounded to the nearest degree produces a decimal that implies far more accuracy than the original reading had.

The sensible rule is to round the answer to roughly the same precision as the number you started with. If you measured to the nearest degree Fahrenheit, an answer carrying six decimal places is not more accurate, it just looks more accurate. For most everyday purposes one or two decimal places is plenty.

Common mistakes to avoid

Converting in the wrong direction

Applying the reverse formula produces an answer that looks plausible but is wildly wrong, and unlike a ratio conversion the error is not a constant factor you might spot by eye. Check the direction against a known fixed point: water freezes at 0 °C and 32 °F.

Using a rounded factor for a long calculation

Rounding the conversion factor before multiplying, then repeating that across many values, compounds the error. Convert with the full factor and round only the final answer.

Converting degrees Fahrenheit to degrees Celsius in a spreadsheet or in code

A one-off answer is what the calculator above is for. When you have a whole column of figures, or you are writing something that has to do the conversion repeatedly, it is worth putting the formula in the tool you are already working in.

Excel and Google Sheets

With your degree Fahrenheit value in cell A1, put this in B1 and fill it down the column:

=(A1 - 32) * 5/9

Excel also ships a built-in CONVERT function that handles many unit pairs directly, but it does not cover every unit and its unit codes are easy to mistype. An explicit formula like the one above is harder to get wrong and shows its working.

Python

def f_to_c(value):
    return (value - 32) * 5 / 9

print(f_to_c(10))

JavaScript

const fToC = (value) => (value - 32) * 5 / 9;

console.log(fToC(10));

Keep the order of operations intact when you translate this into code. Multiplying after adding the offset, rather than before, is the classic bug in temperature conversion and it produces answers that look almost right.

The two measurement systems behind this conversion

This conversion sits on the fault line between the two measurement systems still in everyday use. The metric system was designed in one go in the 1790s as a coherent decimal scheme, where every unit relates to the next by a power of ten. The imperial and US customary systems grew instead by accretion over centuries, which is why their relationships are numbers like 12, 16, 5,280, and 43,560 rather than round ones.

Only three countries have not formally adopted the metric system: the United States, Liberia, and Myanmar. In practice the picture is messier than that, since the US uses metric units throughout science, medicine, and the military, while metric countries still buy screens and tires by the inch. That overlap is exactly why conversions like this one stay necessary.

More questions about degrees Fahrenheit and degrees Celsius

Is the conversion exact or approximate?

Exact. The relationship between the two temperature scales is defined, not measured, so the formula introduces no error at all. Any imprecision in an answer comes from the input figure or from rounding the output, never from the conversion.

Why does the answer have so many decimal places?

The converter shows a high-precision result so that it is never the limiting factor in your calculation. It is up to you to round to something sensible. A measurement taken with a tape measure does not become more accurate because the conversion carried six decimals.

Can I convert in the opposite direction on this page?

Yes. The swap button in the calculator reverses the conversion and carries the current result across as the new input, so you do not have to navigate anywhere or retype anything. The second table above also lists the reverse conversion directly.

Does anything get sent to a server?

No. The arithmetic runs in your browser with a few lines of JavaScript. Nothing you type is uploaded, logged, or stored, which also means the converter keeps working if your connection drops after the page has loaded.

Which figure should I use on an official form?

Use whatever precision the form asks for, and if it does not say, match the precision of the original measurement. For height, weight, and similar personal details, one decimal place is almost always sufficient and often more than is wanted.

Related temperature conversions

If you need to go the other way as a starting point rather than as a swap, the Celsius to Fahrenheit converter is the mirror of this page: same factor, same tables, opposite direction. It is the more natural place to start when most of your figures are already in degrees Celsius.

This is a small category, so the list below reaches into the other measurement families as well:

• CM to Inches - Convert centimeters to inches instantly. Enter any value and get the exact result in decimal inches.
• KG to LBS - Convert kilograms to pounds instantly. Perfect for fitness, cooking, and shipping calculations.
• Liters to Gallons - Convert liters to US gallons quickly. Great for fuel economy, cooking, and tank sizes.
• MPH to KPH - Convert miles per hour to kilometers per hour instantly. Perfect for travel and speed limits.
• Acres to Square Feet - Convert acres to square feet instantly. Ideal for real estate, land surveying, and property measurements.
• Radians to Degrees - Convert radians to degrees instantly. Essential for mathematics, physics, and engineering.

For anything not listed here, the full converter directory covers over a hundred pairs across length, weight, temperature, volume, area, speed, pressure, energy, and more.

Quick reference

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